Absolutely conserved, highly abundant, and present in all cells and organisms studied, polyphosphates (polyPs) are one of the most ancient macromolecules found on earth. They consist of long chains of phosphates, linked by high-energy phosphoanhydride bonds. PolyP has been shown to play crucial roles in bacterial pathogenesis, biofilm formation, stress resistance and blood clotting, and has been implicated in signaling processes and cancer. Despite these important functions, however, little is known about the mechanism(s) by which polyP influences these diverse processes. Based on our most recent discoveries we now postulate that polyP affects this wide and seemingly unrelated range of biological functions by using a single, unifying mechanism: serving as a scaffold that stabilizes protein folding intermediates. This would explain how polyP confers resistance to stress conditions that cause protein unfolding and accelerates processes, such as biofilm formation, which involve the stabilization of amyloid-like proteins in a fiber-forming conformation We propose to investigate the precise mechanism by which polyP influences these processes using a combination of genetic, biochemical, and structural approaches. We will exploit the facts that polyP- deficient bacteria are exquisitely sensitive towards the physiological antimicrobial HOCl (i.e., bleach) and impaired in biofilm formation to develop novel antimicrobials. We will investigate the role of polyP as member of the eukaryotic proteostasis network and expand on our discovery that polyP accelerates disease-related amyloid fiber formation, the leading cause of protein folding diseases, such as Alzheimer's Disease. These studies will reveal polyP's physiological role in eukaryotic organisms, significantly expanding the knowledge about this prebiotic molecule. The results will aid in the development of more effective antimicrobials and strategies to modulate the onset of age-related pathologies.